Apparatus for forming tire-molds.



B. GRANYlLLE. APPARATUS FOR FORMING TIRE MOLDS.

APPLICATION HLED .lAb l. 18. SH. 1,299,456.

Patented Apr. 8, 1919.

3440044 501 3677mm? GranVz'ZZe ammo/vi To all whom/ it may concern: Be it known that'I, BER ARD GRANVILLE, a citizen of the United States of America, residin at New York, in the .county of New ork and Stateof New York, have invented certain new and useful Improvements in- .;.Apparatus for Forming Tireof which the following. is a specification, accompanying drawings;

The invention relates to the art of manufacturing pneumatic tires and other articles formed of vulcanized rubber fabric, and it is the object of the invention to facilitate the. in which the tires manufacture of the molds are fashioned. It is usual to form these molds out of cast metal, the molding surface thereof beingaccurately machined and polished to present a smooth face of the desired contour.- This is a slow and laborious operation, and where, as is usually the case, a large number of duplicate molds are required'in manufacturing the goods, each additional mold increases the delay and expense. With my improved method the machining and polishing operation is entirely eliminated and any number of duplicate molds may be formed from a single master.

- In the drawings:

Figure 1 is a cross-section illustrating the manner of casting-a metallic mold from a master mold;

Fig. 2 is a plan view of one of of the completed mold;

Figs. 3 and 4 views illustrating the manner of compensating for contraction of the metal in cooling.

Inthe construction of molds for the manufacture, of tires there is an outer mold usually formed in complementary sections and a core which is placed within the outer mold. In the drawings 1 have illustrated the method of forming one of the outer m'old sections, but thesame method may be applied to the forming of the core.

As shown, A is a master mold, which is formedrof suitable material having a high fusing point and high rate of heat conduczifon, such as cast iron, steel or other metals alloys. This master mold is accurately the sections machined and polished to correspond to the" melding face of the tire mold, this bei the inner face B of the mold cavity in the ATENT Barman!) GRANVILLE, on NEW YORK, N. Y.

APPARATUS FOR roamlvo, rInE-nonns.

Specification of Letters Patent.

Application filed January 18, 1917. serialize. 143,194, l

reference being had therein to the 'upon;the member C andare diagrannnatic planv men n es. s, 1919:-

construction "shown; TI A is mounted on a membenC offlarger mass, WhlCh may be formed inte'gral therewith,

but is' preferably separately]formedg'saidv member operating in connectiongwith the member A as a chill for quickly absorbing the heat of the castmetal'.

the tire mold, the members A In casting arranged at one side of a mold and C are cavity formed in a sand mold. Preferably the sand 'is placed in a suitable flask, which asshown comprises an outer ring D and inner ring E. tied together by bars J spaced,

around the c rcumference and supported accurately positioned by. guide pins G thereon. A pattern corresponding to the mold cavity H is placed upon the member 0, and the sand is placed in the flask and tamped and struck oil-in the usual manner. There are also formed sprue connections I, which extend through the body of sand and communicate with the mold cavity. After the sand-mold is formed the fi-askis' reversed,.the pattern removed and the flask replaced in the position shown in Fig. 1. then poured into the mold through risers K, which extend to a greater height than the mold cavity and therefore exert a hydrostatic pressure upon the metal therein. The metal coming in contact with the hard surface of the master mold A will be chilled and solidified ina dense structure which is the exact counterpart of the master. Registering lugs L are preferably formed on opposite sides of the mold to receive pins M.

To prevent difficulty in removing the master mold from the mold due to contraction of the latter in'copling, said master mold may be formed in plurality of sections,- as illustrated in Fig. 3. As therein shown, the master is formed of four segmental sections A A A and A, having abutting ends, with a filling of graphite or other suitable material therebetween, indicated at 0 During the process of cooling the pressure exerted by the contraction of the metal will squeeze out the material 0 from be tween the ends of the-adjacent sections of the master mold, thereby contraction and permitting of the easy removal of the master.

- A modified construction for accomplish- The molten metal is compensating for ing the purpose just described is that shown in Fig. 4, in which the outer annular face of the master is covered with a coating P which is squeezed out by the contracting metal, compensating for the decrease in diameter.

The mold sections formed in the manner just described are provided with highly polished dense molding faces, which are superior to the machined and polished surfaces formed by the ordinary process.

Any suitable material may be used as compressible medium for compensating for contraction of the cast-metal, but I preferably employ a mixture of graphiteand kerosene. This material will not spit or produce blow-holes in the cast-metal in contact.

therewith, and at the same time when subjected to the pressure of the contracting metal is sufficiently plastic to be iorced out.

What I claim as my invention 1s:

An apparatus for forming duplicate ineta-llic molds, comprising an annular master mold having a polished surface corresponding to the molding surface of each of the duplicate molds, a plate in heat conducting contact with said master mold and of sufficient'nrass to form therewith a chill, a flask for forming a sand mold to complete the mold cavity around said master mold, and means permitting relative movement of portions of the master mold to compensate for contraction of the cast-metal in contact therewith.

In testimony whereof I atlix my signature.

BERNARD GRANVILLE. 

